diff --git a/Cargo.toml b/Cargo.toml
index ceabe259..89f69179 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -53,75 +53,96 @@ repository = "uuid-rs/uuid"
 [features]
 default = ["std"]
 std = []
-macro-diagnostics = ["uuid-macro-internal"]
+macro-diagnostics = ["private_uuid-macro-internal"]
 
-v1 = ["atomic"]
-v3 = ["md-5"]
+v1 = ["private_atomic"]
+v3 = ["md5"]
 v4 = ["rng"]
-v5 = ["sha-1"]
+v5 = ["sha1"]
 
-js = ["getrandom", "getrandom/js"]
+js = ["private_getrandom", "private_getrandom/js"]
 
-rng = ["getrandom"]
-fast-rng = ["rng", "rand"]
+rng = ["private_getrandom"]
+fast-rng = ["rng", "private_rand"]
 
-# Unstable features (these also need RUSTFLAGS="--cfg uuid_unstable" to work)
-zerocopy-unstable = ["zerocopy"]
+sha1 = ["private_sha1"]
+md5 = ["private_md-5"]
 
-# Private
-[dependencies.getrandom]
+# Public: Used in trait impls on `Uuid`
+[dependencies.serde]
+default-features = false
 optional = true
-version = "0.2"
+version = "1.0.56"
+
+# Public: Used in trait impls on `Uuid`
+[dependencies.slog]
+optional = true
+version = "2"
+
+# Public: Used in trait impls on `Uuid`
+[dependencies.arbitrary]
+optional = true
+version = "1"
+
+# Public (unstable): Used in `zerocopy` derive
+# Unstable: also need RUSTFLAGS="--cfg uuid_unstable" to work
+# This feature may break between releases, or be removed entirely before
+# stabilization. 
+# See: https://github.com/uuid-rs/uuid/issues/588
+[dependencies.zerocopy]
+optional = true
+version = "0.6"
 
 # Private
-[dependencies.rand]
+# Don't depend on this optional feature directly: it may change at any time
+# use the `rng` feature instead
+[dependencies.private_getrandom]
+package = "getrandom"
 optional = true
-version = "0.8"
+version = "0.2"
 
 # Private
-[dependencies.atomic]
-default-features = false
+# Don't depend on this optional feature directly: it may change at any time
+# use the `fast-rng` feature instead
+[dependencies.private_rand]
+package = "rand"
 optional = true
-version = "0.5"
+version = "0.8"
 
 # Private
-[dependencies.md-5]
+# Don't depend on this optional feature directly: it may change at any time
+# Use the `md5` feature instead
+[dependencies.private_md-5]
+package = "md-5"
 default-features = false
 optional = true
 version = "0.10"
 
 # Private
-[dependencies.sha-1]
+# Don't depend on this optional feature directly: it may change at any time
+# Use the `sha1` feature instead
+[dependencies.private_sha1]
+package = "sha1"
 default-features = false
 optional = true
-version = "0.9"
+version = "0.10"
 
 # Public: Re-exported
-[dependencies.uuid-macro-internal]
+# Don't depend on this optional feature directly: it may change at any time
+# Use the `macro-diagnostics` feature instead
+[dependencies.private_uuid-macro-internal]
+package = "uuid-macro-internal"
 version = "1.0.0-alpha.1"
 path = "macros"
 optional = true
 
-# Public: Used in trait impls on `Uuid`
-[dependencies.serde]
+# Private
+# Don't depend on this optional feature directly: it may change at any time
+[dependencies.private_atomic]
+package = "atomic"
 default-features = false
 optional = true
-version = "1.0.56"
-
-# Public: Used in trait impls on `Uuid`
-[dependencies.slog]
-optional = true
-version = "2"
-
-# Public: Used in trait impls on `Uuid`
-[dependencies.arbitrary]
-optional = true
-version = "1"
-
-# Public (unstable): Used in `zerocopy` derive
-[dependencies.zerocopy]
-optional = true
-version = "0.6"
+version = "0.5"
 
 [dev-dependencies.bincode]
 version = "1.0"
diff --git a/src/builder.rs b/src/builder.rs
index 3bff95b6..185abf13 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -544,6 +544,20 @@ impl Builder {
             .with_version(Version::Random)
     }
 
+    /// Creates a `Builder` using the supplied MD5 hashed bytes.
+    pub const fn from_md5_bytes(b: Bytes) -> Self {
+        Builder(Uuid::from_bytes(b))
+            .with_variant(Variant::RFC4122)
+            .with_version(Version::Md5)
+    }
+
+    /// Creates a `Builder` using the supplied SHA1 hashed bytes.
+    pub const fn from_sha1_bytes(b: Bytes) -> Self {
+        Builder(Uuid::from_bytes(b))
+            .with_variant(Variant::RFC4122)
+            .with_version(Version::Sha1)
+    }
+
     /// Creates a `Builder` using the supplied bytes.
     ///
     /// # Errors
diff --git a/src/lib.rs b/src/lib.rs
index c9bb731e..e361612b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -97,7 +97,7 @@
 //! Some features are unstable. They may be incomplete or depend on other
 //! unstable libraries. These include:
 //!
-//! * `zerocopy-unstable` - adds support for zero-copy deserialization using the
+//! * `zerocopy` - adds support for zero-copy deserialization using the
 //!   `zerocopy` library.
 //!
 //! Unstable features may break between minor releases.
@@ -212,10 +212,10 @@ extern crate std;
 extern crate core as std;
 
 // Check that unstable features are accompanied by a the `uuid_unstable` cfg
-#[cfg(all(not(uuid_unstable), feature = "zerocopy-unstable"))]
-compile_error!("The `zerocopy-unstable` feature is unstable and may break between releases. Please also pass `RUSTFLAGS=\"--cfg uuid_unstable\"` to allow it.");
+#[cfg(all(not(uuid_unstable), feature = "zerocopy"))]
+compile_error!("The `zerocopy` feature is unstable and may break between releases. Please also pass `RUSTFLAGS=\"--cfg uuid_unstable\"` to allow it.");
 
-#[cfg(feature = "zerocopy-unstable")]
+#[cfg(feature = "zerocopy")]
 use zerocopy::{AsBytes, FromBytes, Unaligned};
 
 mod builder;
@@ -235,6 +235,10 @@ mod v5;
 
 #[cfg(feature = "rng")]
 mod rng;
+#[cfg(feature = "md5")]
+mod md5;
+#[cfg(feature = "sha1")]
+mod sha1;
 
 mod external;
 
@@ -243,7 +247,7 @@ mod macros;
 
 #[doc(hidden)]
 #[cfg(feature = "macro-diagnostics")]
-pub extern crate uuid_macro_internal;
+pub extern crate private_uuid_macro_internal;
 
 use crate::std::convert;
 
@@ -392,7 +396,7 @@ pub enum Variant {
 /// The `Uuid` type is always guaranteed to be have the same ABI as [`Bytes`].
 #[derive(Clone, Copy, Eq, Hash, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(
-    feature = "zerocopy-unstable",
+    feature = "zerocopy",
     derive(AsBytes, FromBytes, Unaligned)
 )]
 #[repr(transparent)]
diff --git a/src/macros.rs b/src/macros.rs
index de200486..7136718a 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -5,7 +5,7 @@ macro_rules! define_uuid_macro {
         #[macro_export]
         macro_rules! uuid {
             ($uuid:literal) => {{
-                $crate::Uuid::from_bytes($crate::uuid_macro_internal::parse_lit!($uuid))
+                $crate::Uuid::from_bytes($crate::private_uuid_macro_internal::parse_lit!($uuid))
             }};
         }
 
diff --git a/src/md5.rs b/src/md5.rs
new file mode 100644
index 00000000..3eb21fe8
--- /dev/null
+++ b/src/md5.rs
@@ -0,0 +1,14 @@
+#[cfg(feature = "v3")]
+pub(crate) fn hash(ns: &[u8], src: &[u8]) -> [u8; 16] {
+    use private_md_5::{Md5, Digest};
+
+    let mut hasher = Md5::new();
+
+    hasher.update(ns);
+    hasher.update(src);
+
+    let mut bytes = [0; 16];
+    bytes.copy_from_slice(&hasher.finalize()[..16]);
+
+    bytes
+}
diff --git a/src/rng.rs b/src/rng.rs
index 17859db8..fa21b626 100644
--- a/src/rng.rs
+++ b/src/rng.rs
@@ -4,7 +4,7 @@ pub(crate) fn bytes() -> [u8; 16] {
     {
         let mut bytes = [0u8; 16];
 
-        getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
+        private_getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
             // NB: getrandom::Error has no source; this is adequate display
             panic!("could not retrieve random bytes for uuid: {}", err)
         });
@@ -14,7 +14,7 @@ pub(crate) fn bytes() -> [u8; 16] {
 
     #[cfg(feature = "fast-rng")]
     {
-        rand::random()
+        private_rand::random()
     }
 }
 
@@ -24,7 +24,7 @@ pub(crate) fn u16() -> u16 {
     {
         let mut bytes = [0u8; 2];
 
-        getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
+        private_getrandom::getrandom(&mut bytes).unwrap_or_else(|err| {
             // NB: getrandom::Error has no source; this is adequate display
             panic!("could not retrieve random bytes for uuid: {}", err)
         });
@@ -34,6 +34,6 @@ pub(crate) fn u16() -> u16 {
 
     #[cfg(feature = "fast-rng")]
     {
-        rand::random()
+        private_rand::random()
     }
 }
diff --git a/src/sha1.rs b/src/sha1.rs
new file mode 100644
index 00000000..da0e00e3
--- /dev/null
+++ b/src/sha1.rs
@@ -0,0 +1,14 @@
+#[cfg(feature = "v5")]
+pub(crate) fn hash(ns: &[u8], src: &[u8]) -> [u8; 16] {
+    use private_sha1::{Sha1, Digest};
+
+    let mut hasher = Sha1::new();
+
+    hasher.update(ns);
+    hasher.update(src);
+
+    let mut bytes = [0; 16];
+    bytes.copy_from_slice(&hasher.finalize()[..16]);
+
+    bytes
+}
diff --git a/src/v1.rs b/src/v1.rs
index 86716baf..c8b425e0 100644
--- a/src/v1.rs
+++ b/src/v1.rs
@@ -5,7 +5,7 @@
 
 use crate::{Uuid, Version};
 
-use atomic::Atomic;
+use private_atomic::{Atomic, Ordering};
 
 /// The number of 100 ns ticks between the UUID epoch
 /// `1582-10-15 00:00:00` and the Unix epoch `1970-01-01 00:00:00`.
@@ -295,7 +295,7 @@ impl ClockSequence for Context {
         // increment the clock sequence we want to wrap once it becomes larger
         // than what we can represent in a "u14". Otherwise there'd be patches
         // where the clock sequence doesn't change regardless of the timestamp
-        self.count.fetch_add(1, atomic::Ordering::AcqRel) % (u16::MAX >> 2)
+        self.count.fetch_add(1, Ordering::AcqRel) % (u16::MAX >> 2)
     }
 }
 
diff --git a/src/v3.rs b/src/v3.rs
index 2fa06114..d529f3ee 100644
--- a/src/v3.rs
+++ b/src/v3.rs
@@ -1,6 +1,4 @@
-use crate::{Uuid, Variant, Version};
-
-use md5::{Digest, Md5};
+use crate::Uuid;
 
 impl Uuid {
     /// Creates a UUID using a name from a namespace, based on the MD5
@@ -32,22 +30,7 @@ impl Uuid {
     /// [`NAMESPACE_URL`]: #associatedconstant.NAMESPACE_URL
     /// [`NAMESPACE_X500`]: #associatedconstant.NAMESPACE_X500
     pub fn new_v3(namespace: &Uuid, name: &[u8]) -> Uuid {
-        let mut hasher = Md5::new();
-
-        hasher.update(namespace.as_bytes());
-        hasher.update(name);
-
-        let buffer = hasher.finalize();
-
-        let mut bytes = crate::Bytes::default();
-        bytes.copy_from_slice(&buffer[..16]);
-
-        let mut builder = crate::Builder::from_bytes(bytes);
-        builder
-            .set_variant(Variant::RFC4122)
-            .set_version(Version::Md5);
-
-        builder.into_uuid()
+        crate::Builder::from_md5_bytes(crate::md5::hash(namespace.as_bytes(), name)).into_uuid()
     }
 }
 
@@ -58,7 +41,10 @@ mod tests {
     #[cfg(target_arch = "wasm32")]
     use wasm_bindgen_test::*;
 
-    use crate::std::string::ToString;
+    use crate::{
+        Variant, Version,
+        std::string::ToString,
+    };
 
     static FIXTURE: &'static [(&'static Uuid, &'static str, &'static str)] = &[
         (
diff --git a/src/v5.rs b/src/v5.rs
index 7e4ab326..f8396423 100644
--- a/src/v5.rs
+++ b/src/v5.rs
@@ -1,6 +1,4 @@
-use crate::{Uuid, Variant, Version};
-
-use sha1::{Digest, Sha1};
+use crate::Uuid;
 
 impl Uuid {
     /// Creates a UUID using a name from a namespace, based on the SHA-1 hash.
@@ -31,22 +29,7 @@ impl Uuid {
     /// [`NAMESPACE_URL`]: struct.Uuid.html#associatedconst.NAMESPACE_URL
     /// [`NAMESPACE_X500`]: struct.Uuid.html#associatedconst.NAMESPACE_X500
     pub fn new_v5(namespace: &Uuid, name: &[u8]) -> Uuid {
-        let mut hasher = Sha1::new();
-
-        hasher.update(namespace.as_bytes());
-        hasher.update(name);
-
-        let buffer = hasher.finalize();
-
-        let mut bytes = crate::Bytes::default();
-        bytes.copy_from_slice(&buffer[..16]);
-
-        let mut builder = crate::Builder::from_bytes(bytes);
-        builder
-            .set_variant(Variant::RFC4122)
-            .set_version(Version::Sha1);
-
-        builder.into_uuid()
+        crate::Builder::from_sha1_bytes(crate::sha1::hash(namespace.as_bytes(), name)).into_uuid()
     }
 }
 
@@ -57,7 +40,10 @@ mod tests {
     #[cfg(target_arch = "wasm32")]
     use wasm_bindgen_test::*;
 
-    use crate::std::string::ToString;
+    use crate::{
+        Variant, Version,
+        std::string::ToString,
+    };
 
     static FIXTURE: &'static [(&'static Uuid, &'static str, &'static str)] = &[
         (